This 5.1 MHz circuit was found in a 1980s documentation. The frequency is given by the crystal and general purpose transistors can be used.
This sensitive electrostatic charge detector uses only common discrete components. The circuit can be...
Found in a 90s Popular Electronics, this circuit uses a 741 to generate frequencies from 0.1 to 30...
This circuit allows you to read temperatures with a common digital voltmeter. We found it in the...